如何用PowerMockito 测试静态方法

假如有下面一个类DemoStatic，它里面定义了各种静态方法，这些静态方法可能是一些Utilities方法，辅助其它的类。

package mock.demo;

public class DemoStatic {

	public static String sayHello() {
		return "Hello";
	}
	
	public static String saySomething(String word) {
		return word;
	}	
	
	public static void sayAgain() {
		System.out.println(getMyWord());
	}	
	
	private static String getMyWord() {
		return "This is my word";
	}
}

首先，我们写一个测试类DemoStaticTest.java, 如下：

@RunWith(PowerMockRunner.class)
@PrepareForTest({DemoStatic.class})
public class DemoStaticTest {

}

注意在类的前面要加这个annotation:

@PrepareForTest({DemoStatic.class})

其次，需要在你的项目中加入下面的maven依赖：

		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-api-mockito</artifactId>
			<version>1.4.10</version>
		</dependency>
		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-module-junit4</artifactId>
			<version>1.4.10</version>
		</dependency>

• Mock 无参数的静态方法

	@Test
	public void testMockSayHello() {
		PowerMockito.spy(DemoStatic.class);
		PowerMockito.when(DemoStatic.sayHello()).thenReturn("my hello");
		
		System.out.println(DemoStatic.sayHello());  // my hello
	}

• Mock 带参数的静态方法

	@Test
	public void testSaySomething() throws Exception {
		PowerMockito.spy(DemoStatic.class);
		PowerMockito.when(DemoStatic.class, "saySomething", Mockito.anyString()).thenReturn("something to say!");
		
		System.out.println(DemoStatic.saySomething("say hello")); //something to say!
	}

• Mock private 静态方法

	@Test
	public void testMockPrivate() throws Exception {
		PowerMockito.spy(DemoStatic.class);
		PowerMockito.when(DemoStatic.class, "getMyWord").thenReturn("Nothing to say");
		
		DemoStatic.sayAgain(); //Nothing to say
	}